But I agree with you, I don’t see how the “viewfinder” is all that useful, other than “nifty!”.
Humans can learn this stuff, cameras with crude viewfinders have appeared in the past.
The best version of your complaint is that the viewfinder does not have accurate frame lines that account for parallax at various distances, which is true, but there are still ways of using the viewfinder to assist in composition.
If you take two or three shots at two meters, and look at what the camera captured versus where your composition was in the frame, you can immediately intuit a baseline for where the frame lines 'should be' on the viewfinder at two meters. "Occupies the bottom right two thirds of the viewfinder" for example.
Without a reference frame, these intuitions (and your aiming of the camera!) are going to be far less accurate.
Often switching from using your eye to looking through the viewfinder and fiddle with composition is how you ruin a genuine shot and miss the moment.
Also I used a camera without a viewfinder for some years, I guarantee if it's a fixed lens you learn what you get quickly.
(“Ansely Adam’s”, WTF, autocorrect?)